This legislation addresses the widespread issue of per- and polyfluoroalkyl substances (PFAS) exposure in the United States, noting that these chemicals are detected in millions of Americans and drinking water, are linked to chronic diseases, and currently lack a federal statutory cause of action for harm. Its core purposes are to encourage PFAS research, provide accountability for irresponsible manufacturing, and codify harm from significant exposure as an injury, shifting medical monitoring costs to responsible parties. The bill amends the Toxic Substances Control Act to establish a federal cause of action, allowing individuals significantly exposed to PFAS to sue manufacturers who foresaw or should have foreseen human exposure. Courts may award medical monitoring if the individual has been significantly exposed, faces an increased risk of developing a PFAS-associated disease, and requires periodic diagnostic examinations beyond routine care. To aid in proving exposure, the bill creates presumptions of significant exposure if a defendant's manufacturing process released PFAS into an area of exposure for at least one year, or if PFAS are detected in the individual's body or blood serum. Defendants can rebut this presumption with independent testing, the cost of which they must bear. Additionally, courts can lower the standard for scientific proof regarding increased disease risk if toxicological data is insufficient and may order new studies to generate reliable data. Crucially, this Act clarifies that it does not preempt, alter, or preclude any existing state law claims or remedies, ensuring it is not an exclusive claim or remedy for PFAS-related harm.